Nasogastric tubes and related devices are described in U.S. Pat. Nos. 5,643,230, 5,417,664, 5,011,474, 5,000,175, 4,821,715, 4,787,894, 4,735,607, 4,699,138, 4,508,533, and 4,214,593. Nasogastric tubes and related devices are also described in the following patents and published patent applications: EP 0500778, JP 10179677, WO 9716154, WO 9631248, and WO 8000538.
Nasogastric tubes are used to aspirate food contents from the stomach or to feed patients who are unable to safely feed themselves. Nasogastric tubes are commonly used in the operating room, intensive care units, home care, and in hospice settings. Prior art nasogastric tubes are frequently used to aspirate stomach contents. However, in some cases, aspiration of the stomach contents results in micro-aspirations that can cause nosocomial infections.
Similar problems can occur with prior art laryngeal masks. Laryngeal masks are used to provide ventilation and are commonly used in the operating room and in situations where it is difficult to insert an endotracheal tube. Prior art laryngeal masks and related devices are described in U.S. Pat. Nos. 4,351,328, 4,509,514, 4,995,388, 5,241,956, 5,303,697, 5,355,879, 5,632,271, 5,878,745, 6,631,720 and 6,895,966 and in published international patent application no. WO 1994/02191. A disadvantage of prior art laryngeal masks is that there is no protection from aspiration into the lungs of gastric contents or saliva regurgitated into the hypopharynx and pharynx.